Submarine drive systems are generally provided with a DC power supply system for the supply of the electric drives of the submarine, for example the supply of propeller drives. In many cases, energy stores configured in the form of batteries are associated with the DC power supply system. Batteries are customarily combined in battery modules, and a number of such battery modules are connected in series to form a battery string. In order to deliver the high battery capacities required for the supply of submarine drives, it is customary to connect a number of battery strings in parallel.
A drive system of this type for a submarine is known, for example, from DE 102007053229 A1. In addition to a DC power supply system, the drive system comprises a number of battery strings, each comprising a plurality of series-connected battery modules. The battery strings are each connected to the DC power supply system by means of a string connection unit, via which the battery string can be selectively connected to the DC power supply system or disconnected from the DC power supply system. Accordingly, in the event of an increased current in the battery string, for example further to a short-circuit, it is possible to isolate the battery string from the DC power supply system by means of the string connection unit.
In practice, the short-circuit protection function of the known drive system is entirely proven. In the known drive system, however, it has emerged that the overcharging and/or exhaustive discharging of the battery strings cannot be effectively prevented. Specifically, this is problematic where battery modules configured as lithium-ion batteries are to be used. The overcharging or exhaustive discharging of battery modules can result in irreversible damage to the battery modules, e.g. associated with exothermic breakdown reactions. The service life of battery modules, and the availability of the drive system, are reduced accordingly.